whalintranscoder.java

memcached JAVA客户端API,应用广泛,运行比较稳定。

package net.spy.memcached.transcoders;

import java.util.Date;

import net.spy.memcached.CachedData;

/**
 * Transcoder that provides compatibility with Greg Whalin's memcached client.
 */
public class WhalinTranscoder extends BaseSerializingTranscoder
	implements Transcoder<Object> {

	static final int SPECIAL_BYTE = 1;
	static final int SPECIAL_BOOLEAN = 8192;
	static final int SPECIAL_INT = 4;
	static final int SPECIAL_LONG = 16384;
	static final int SPECIAL_CHARACTER = 16;
	static final int SPECIAL_STRING = 32;
	static final int SPECIAL_STRINGBUFFER = 64;
	static final int SPECIAL_FLOAT = 128;
	static final int SPECIAL_SHORT = 256;
	static final int SPECIAL_DOUBLE = 512;
	static final int SPECIAL_DATE = 1024;
	static final int SPECIAL_STRINGBUILDER = 2048;
	static final int SPECIAL_BYTEARRAY = 4096;
	static final int COMPRESSED = 2;
	static final int SERIALIZED = 8;

	private final TranscoderUtils tu=new TranscoderUtils(false);

	/* (non-Javadoc)
	 * @see net.spy.memcached.Transcoder#decode(net.spy.memcached.CachedData)
	 */
	public Object decode(CachedData d) {
		byte[] data=d.getData();
		Object rv=null;
		if((d.getFlags() & COMPRESSED) != 0) {
			data=decompress(d.getData());
		}
		if((d.getFlags() & SERIALIZED) != 0) {
			rv=deserialize(data);
		} else {
			int f=d.getFlags() & ~COMPRESSED;
			switch(f) {
				case SPECIAL_BOOLEAN:
					rv=Boolean.valueOf(this.decodeBoolean(data));
					break;
				case SPECIAL_INT:
					rv=new Integer(tu.decodeInt(data));
					break;
				case SPECIAL_SHORT:
					rv=new Short((short)tu.decodeInt(data));
					break;
				case SPECIAL_LONG:
					rv=new Long(tu.decodeLong(data));
					break;
				case SPECIAL_DATE:
					rv=new Date(tu.decodeLong(data));
					break;
				case SPECIAL_BYTE:
					rv=new Byte(tu.decodeByte(data));
					break;
				case SPECIAL_FLOAT:
					rv=new Float(Float.intBitsToFloat(tu.decodeInt(data)));
					break;
				case SPECIAL_DOUBLE:
					rv=new Double(Double.longBitsToDouble(tu.decodeLong(data)));
					break;
				case SPECIAL_BYTEARRAY:
					rv=data;
					break;
				case SPECIAL_STRING:
					rv = decodeString(data);
					break;
				case SPECIAL_STRINGBUFFER:
					rv=new StringBuffer(decodeString(data));
					break;
				case SPECIAL_STRINGBUILDER:
					rv=new StringBuilder(decodeString(data));
					break;
				case SPECIAL_CHARACTER:
                                        rv = decodeCharacter(data);
                                        break;
				default:
					getLogger().warn("Cannot handle data with flags %x", f);
			}
		}
		return rv;
	}

	public CachedData encode(Object o) {
		byte[] b=null;
		int flags=0;
		if(o instanceof String) {
			b=encodeString((String)o);
			flags |= SPECIAL_STRING;
		} else if(o instanceof StringBuffer) {
			flags |= SPECIAL_STRINGBUFFER;
			b=encodeString(String.valueOf(o));
		} else if(o instanceof StringBuilder) {
			flags |= SPECIAL_STRINGBUILDER;
			b=encodeString(String.valueOf(o));
		} else if(o instanceof Long) {
			b=tu.encodeLong((Long)o);
			flags |= SPECIAL_LONG;
		} else if(o instanceof Integer) {
			b=tu.encodeInt((Integer)o);
			flags |= SPECIAL_INT;
		} else if(o instanceof Short) {
			b=tu.encodeInt((Short)o);
			flags |= SPECIAL_SHORT;
		} else if(o instanceof Boolean) {
			b=this.encodeBoolean((Boolean)o);
			flags |= SPECIAL_BOOLEAN;
		} else if(o instanceof Date) {
			b=tu.encodeLong(((Date)o).getTime());
			flags |= SPECIAL_DATE;
		} else if(o instanceof Byte) {
			b=tu.encodeByte((Byte)o);
			flags |= SPECIAL_BYTE;
		} else if(o instanceof Float) {
			b=tu.encodeInt(Float.floatToIntBits((Float)o));
			flags |= SPECIAL_FLOAT;
		} else if(o instanceof Double) {
			b=tu.encodeLong(Double.doubleToLongBits((Double)o));
			flags |= SPECIAL_DOUBLE;
		} else if(o instanceof byte[]) {
			b=(byte[])o;
			flags |= SPECIAL_BYTEARRAY;
		} else if (o instanceof Character) {
			b = tu.encodeInt((Character) o);
			flags |= SPECIAL_CHARACTER;
		} else {
			b=serialize(o);
			flags |= SERIALIZED;
		}
		assert b != null;
		if(b.length > compressionThreshold) {
			byte[] compressed=compress(b);
			if(compressed.length < b.length) {
				getLogger().info("Compressed %s from %d to %d",
						o.getClass().getName(), b.length, compressed.length);
				b=compressed;
				flags |= COMPRESSED;
			} else {
				getLogger().info(
					"Compression increased the size of %s from %d to %d",
					o.getClass().getName(), b.length, compressed.length);
			}
		}
		return new CachedData(flags, b);
	}

	protected Character decodeCharacter(byte[] b){
		return Character.valueOf((char)tu.decodeInt(b));
	 }

	public byte[] encodeBoolean(boolean b){
		byte[] rv = new byte[1];
		rv[0] = (byte) (b ? 1 : 0);
		return rv;
	}

	public boolean decodeBoolean(byte[] in) {
		assert in.length == 1 : "Wrong length for a boolean";
		return in[0] == 1;
	}


}